A sub-1-V bulk-driven opamp with an effective transconductance-stabilizing technique

Nghia Tang; Wookpyo Hong; Jong Hoon Kim; Youngoo Yang; Deukhyoun Heo

doi:10.1109/TCSII.2015.2455471

A sub-1-V bulk-driven opamp with an effective transconductance-stabilizing technique

Nghia Tang
, Wookpyo Hong
, Jong Hoon Kim
, Youngoo Yang
, Deukhyoun Heo

Department of Electronic and Electrical Engineering

Research output: Contribution to journal › Article › peer-review

19 Scopus citations

Abstract

The effective transconductance (G_m) of a bulk-driven operational amplifier (opamp) can significantly vary with the input common-mode voltage. This variation of G_m complicates frequency compensation and creates harmonic distortion. Thus, this brief presents a G_m-stabilizing technique to reduce the variation of G_m across the input common-mode range (ICMR). The idea is to use a variable positive feedback structure to adaptively control G_m to the input common-mode voltage. A low-voltage bulk-driven opamp with the proposed G_m-stabilizing technique has been implemented in a 0.18-μm n-well CMOS process. The opamp consumes 261 μW from a 900-mV supply voltage. The variation of G_m is reduced from 132% to 25% across the rail-to-rail ICMR. The measured dc gain is 76.8 dB and the unity-gain bandwidth is 7.11 MHz when the opamp is loaded with 17pF∥1 MΩ.

Original language	English
Article number	7155507
Pages (from-to)	1018-1022
Number of pages	5
Journal	IEEE Transactions on Circuits and Systems II: Express Briefs
Volume	62
Issue number	11
DOIs	https://doi.org/10.1109/TCSII.2015.2455471
State	Published - 1 Nov 2015

Keywords

bulk-driven input stage
effective transconductance
low voltage
rail-to-rail operational amplifier

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10.1109/TCSII.2015.2455471

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title = "A sub-1-V bulk-driven opamp with an effective transconductance-stabilizing technique",

abstract = "The effective transconductance (Gm) of a bulk-driven operational amplifier (opamp) can significantly vary with the input common-mode voltage. This variation of Gm complicates frequency compensation and creates harmonic distortion. Thus, this brief presents a Gm-stabilizing technique to reduce the variation of Gm across the input common-mode range (ICMR). The idea is to use a variable positive feedback structure to adaptively control Gm to the input common-mode voltage. A low-voltage bulk-driven opamp with the proposed Gm-stabilizing technique has been implemented in a 0.18-μm n-well CMOS process. The opamp consumes 261 μW from a 900-mV supply voltage. The variation of Gm is reduced from 132\% to 25\% across the rail-to-rail ICMR. The measured dc gain is 76.8 dB and the unity-gain bandwidth is 7.11 MHz when the opamp is loaded with 17pF∥1 MΩ.",

keywords = "bulk-driven input stage, effective transconductance, low voltage, rail-to-rail operational amplifier",

author = "Nghia Tang and Wookpyo Hong and Kim, \{Jong Hoon\} and Youngoo Yang and Deukhyoun Heo",

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AU - Heo, Deukhyoun

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N2 - The effective transconductance (Gm) of a bulk-driven operational amplifier (opamp) can significantly vary with the input common-mode voltage. This variation of Gm complicates frequency compensation and creates harmonic distortion. Thus, this brief presents a Gm-stabilizing technique to reduce the variation of Gm across the input common-mode range (ICMR). The idea is to use a variable positive feedback structure to adaptively control Gm to the input common-mode voltage. A low-voltage bulk-driven opamp with the proposed Gm-stabilizing technique has been implemented in a 0.18-μm n-well CMOS process. The opamp consumes 261 μW from a 900-mV supply voltage. The variation of Gm is reduced from 132% to 25% across the rail-to-rail ICMR. The measured dc gain is 76.8 dB and the unity-gain bandwidth is 7.11 MHz when the opamp is loaded with 17pF∥1 MΩ.

AB - The effective transconductance (Gm) of a bulk-driven operational amplifier (opamp) can significantly vary with the input common-mode voltage. This variation of Gm complicates frequency compensation and creates harmonic distortion. Thus, this brief presents a Gm-stabilizing technique to reduce the variation of Gm across the input common-mode range (ICMR). The idea is to use a variable positive feedback structure to adaptively control Gm to the input common-mode voltage. A low-voltage bulk-driven opamp with the proposed Gm-stabilizing technique has been implemented in a 0.18-μm n-well CMOS process. The opamp consumes 261 μW from a 900-mV supply voltage. The variation of Gm is reduced from 132% to 25% across the rail-to-rail ICMR. The measured dc gain is 76.8 dB and the unity-gain bandwidth is 7.11 MHz when the opamp is loaded with 17pF∥1 MΩ.

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KW - low voltage

KW - rail-to-rail operational amplifier

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A sub-1-V bulk-driven opamp with an effective transconductance-stabilizing technique

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Keywords

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